POSTER ABSTRACTS
Cardiology/Respiratory P01
COMPARISON OF GATED HEART BLOOD POOL STUDIES USING NOVEL CADMIUM-ZINC-TELLURIDE SPECT IMAGING TECHNOLOGY WITH CONVENTIONAL ANGER CAMERA PLANAR IMAGING
Emma Fleming , Barbara Bedford , Hugh Dixon , Chuong Bui , Quee Li Chiam , Kien Lee
Bankstown-Lidcombe Hospital, NSW, Australia
Background: Novel dedicated cardiac cameras using cadmium-zinc-tellu- ride (CZT) technology, primarily used for myocardial perfusion imaging, have dramatically higher performance than conventional Anger cameras.
Using this novel technology to perform gated heart pool scans (GHPS) has the potential to improve effi ciency, patient experience and dosimetry.
Aim: To compare the assessment of left-ventricular ejection fraction (LVEF) and function using CZT-SPECT imaging (GE570c) to conventional planar imaging (GE670).
Methods: 44 patients attending for GHPS were studied using conventional planar imaging (GE670), immediately followed by a 5 minute CZT-SPECT acquisition (GE570c). Planar images were manually processed to calculate the planar-LVEF (pLVEF). CZT-SPECT images were processed with an automated algorithm to calculate SPECT-LVEF (sLVEF). Wall motion was assessed visually in both studies.
Results: One patient was technically unsuccessful due large body habitus (BMI = 55) causing image truncation on GE570c. In 4 patients the sLVEF measurement was unsatisfactory due to poor edge detection by the auto- mated algorithm where there was adjacent increased gut or liver activity.
However the automated algorithm for sLVEF was highly reproducible with retest correlation of 0.997. For the remaining 39 patients, using the linear regression equation y = mx + b, where y = sLVEF; x = pLVEF; Slope, m = 0.95;
Intercept, b = 2.35%; Correlation, r = 0.82. All 6 reporting physicians found CZT-SPECT useful to assess regional wall motion abnormalities in all dimensions and to quantify absolute end diastolic and end systolic volumes.
Conclusion: Measurement of LVEF using CZT-SPECT imaging correlated well with conventional planar imaging. Technical limitations arose in very large patients and in patients with increased gut and liver activity. CZT-SPECT is a useful three-dimensional imaging technique which increases reporter confi - dence in assessing wall motion abnormalities and in quantifying volumes. It has a promising role in GHPS to signifi cantly reduce imaging time and dose.
P02
PROSTHETIC VALVE INFECTION AND THE USE OF F -18 FDG PET/CT
Nicole Kearney 1 , Suresh Viswanathan 2 , Samuel Adera 2 1 Hunter New England Imaging, NSW, Australia 2 Hunter New England Health, NSW, Australia
Background: A 74 year old male with previous history of myocardial infarction, CABG, aortic valve and aortic root replacement presented with Salmonella sepsis with an unknown source. The patient commenced intravenous ceftriaxone on admission to hospital and due to his prosthetic aortic valve infective endocarditis (IE) was strongly suspected. Both transthoracic (TTE) and transoesophageal (TOE) echocardiograms showed no evidence of vegetation or aortic root abscess. CT performed of the abdomen and thorax failed to demonstrate any source of infection. On the fi fth day of hospital admission he developed bradycardia due to intermittent atrioventricular block resulting in the insertion of a dual chamber pacemaker.
Method & Results: F-18 FDG PET/CT images demonstrated abnormal tracer accumulation in the root of the aorta extending to the site of valve prosthesis and in the anterior portion of the root of the aorta, at the site of an aneurysm, increased lung uptake in the upper right lobe and bilateral effusions.
Discussion: TOE has a sensitivity of between 90 and 100% when detecting vegetations associated with IE. This fi gure decreases to 50% in the presence of a prosthetic valve. FDG PET/CT, while nonspecifi c in nature, is highly sensitive for detecting foci of infection and has a high negative predictive value, and hence may have a role in detecting endocarditis/prosthetic valve infection. One week following the PET scan a repeat TOE was consistent with development of aortic root abscess.
Conclusion: This case demonstrates the usefulness of F-18 FDG PET/CT in diagnosing IE more accurately than TOE or TTE, which are usually con- sidered the gold standard, and thereby facilitating the management of this relatively rare condition that carries signifi cant mortality.
P03
‘AIR TRAPPING’ AS A CAUSE FOR VQ SPECT PERFUSION MISMATCH
Kenny Sek , Charles Werren , Teck Siew , Michael McCarthy
Royal Perth Hospital, Perth, Australia
Background: The more widespread adoption of VQ SPECT and SPECT-CT has led to the increased detection of VQ mismatches. In some cases, this can be
Figure 1 Comparison of LVEF measurement with CZT-SPECT (sLVEF) to planar (pLVEF) imaging.
attributed to apparent increased ventilation as seen with the physiologic ‘rind’
effect in VQ SPECT. A similar effect can be seen in the setting of some pulmo- nary parenchymal pathology which causes apparent ‘air-trapping’, leading to areas of marked perfusion reduction but maintained ventilation. This appears to be most common in the setting of emphysematous change. While this can be easily recognised if it is part of a diffuse emphysematous process, regional or more localised lung parenchymal change can be more diffi cult to recognise.
Aim: We would like to highlight the potential of this ‘air-trapping’ phenom- enon in causing perfusion mismatch, resulting in a false positive VQ scan, and to explore features of ventilation-perfusion abnormalities on VQ SPECT that could be helpful in differentiating non-embolic versus embolic causes.
Method and Results: We present three cases where underlying lung disease leads to at least partial perfusion mismatch. Discussion regarding the under- lying pathophysiology will be presented. We will explore certain unique scin- tigraphic features of this ‘air-trapping’ phenomenon and the role of the CT component of SPECT-CT or CT chest will be emphasised.
Case 1: Congenital sublobar emphysema Case 2: Bronchiolitis obliterans Case 3: Interstitial pulmonary fi brosis
Conclusion: These cases illustrate the fact that a variety of pulmonary parenchymal pathology can lead to pulmonary vascular changes causing perfusion mismatch. An expansile or bulging border around a ventilation or perfusion abnormality should raise the suspicion that apparent perfusion mismatch could be due to ‘air-trapping’ phenomenon. Correlative anatomic information from CT images is particularly useful in confi rming the presence of this phenomenon as a potential mimicker of pulmonary embolism.
P04
UNRECOGNISED MYOCARDIAL ISCHAEMIA ON ONCOLOGICAL FDG - PET
Kelvin Yap , Ganesh Ramaseshan , Kylie O ’ Halloran , Kim Taubman , Stephen Schlicht
Medical Imaging Department, St. Vincent ’ s Hospital Melbourne, Victoria, Australia
Background: Cardiac FDG uptake can be highly variable and non-uniform uptake is often dismissed as normal in this location. We present a case, where failure to recognise an important pattern almost led to adverse patient outcome.
Method: 67 y.o. man with head and neck malignancy, underwent preopera- tive staging PET at another institution. He was planned for partial glossec- tomy and neck dissection.
During the anaesthetic induction, signifi cant ischaemic ECGs changes caused the operation to be aborted. Subsequent adenosine sestamibi dem- onstrated a small LAD infarct with signifi cant peri-infract ischaemia. Coro- nary angiogram demonstrated triple vessel disease requiring surgical management. Semi-urgent coronary artery bypass grafts, were performed with good recovery. Patient the subsequently underwent an uneventful left partial glossectomy and neck dissection with complete clearance.
This case was identifi ed, when he was referred for urgent inpatient myocar- dial perfusion study. Review of his staging FDG-PET demonstrated unre- ported intense LAD territory uptake. Literature review and discussion with PET specialists, confi rmed the presence of ischaemic or hibernating myocardium.
Results: Cardiac uptake of FDG, during routine oncological studies can be highly variable. depending on the length of fasting. After suffi ciently long fasting period (typically > 12 hours) the myocardial metabolism shifts to fatty acids as a source of energy. It has been well recognised by Gropler et al (1999), the septum and anterior wall containing signifi cantly less activity than the lateral and posterior walls.
Conclusion: Despite the limitation of variable regional cardiac uptake during routine oncological FDG-PET, it should be recognised that increased uptake in the anterior and septal walls, is abnormal, and hibernating/isch- aemic myocardium should be excluded with other investigations. The failure to recognise this abnormal pattern may lead to adverse outcomes.
Molecular Imaging P05
DEVELOPING NATIONAL CAPABILITY FOR THE PRODUCTION AND USE OF RADIOMETAL BASED RADIOPHARMACEUTICALS
Nigel Lengk, Paul Pellegrini , Elisabeth Oehlke , Benjamin Fraser , Ivan Greguric
ANSTO, Lucas Heights, NSW, Australia
Radiometals remain key radioisotopes for radio-medicine; the mainstay diag- nostic medical imaging isotope, 99m Tc, and important radioisotopes for radio- therapy, 90 Y and 153 Sm. However, the worldwide growth in PET centres, driven by the wildly successful [ 18 F]-FDG, has provided a yet to be seized opportunity to deliver radiometal-based radiopharmaceuticals with clinical relevance to researchers. An ever growing set of radiometals is becoming available in Australia covering a wide range of half-lives, nuclear and chemical properties, these include 64 Cu, 68 Ga, 86 Y, 89 Zr, and looking into the near future, 44 Sc, 45 Ti and 90 Nb.
ANSTO ’ s Lifesciences division is working to provide the Australian academic and clinical communities access to the following key areas.
Radioisotope supply
Two in-house 68 Ge/ 68 Ga generators; one solely for research and a larger generator for pre-clinical trials, provide access to this key radioisotope.
ANSTO has provided fi nancial and technical support to numerous cyclotron centres around Australia for development of solid targetry facilities, ensuring supply of 124 I, 64 Cu, 86 Y and 89 Zr in the short-term and 44 Sc, 45 Ti and 90 Nb later. In coming years the OPAL reactor will begin producing pharmaceutical grade 177 Lu as part of the Australian government ’ s investment in nuclear medicine.
Radiometal Labelling Research and Development
In addition to our programs developing new ligands, tracers and improved radiometal labelling procedures, Lifesciences is supporting the development of new biomolecule treatments by providing researchers access to laborato- ries, procedures and expertise tailored specifi cally for functionalising bio- molecules for radiometal labelling.
Preclinical Radiometal Tracer Development
We are working to deliver novel radiometal-based diagnostic tracers to the Australian research and clinical community by accessing the pre-clinical programs of our key international partnerships at Memorial Sloan Kettering Cancer Centre and Massachusetts General Hospital. Our initial objective is to supply the antibodies, i.e. [ 89 Zr]-J591. As our supply radiometals is diversi- fi ed we will expand into proteins, peptides and other biomolecules.
P06
PERFORMANCE EVALUATION OF PRECLINICAL PET SCANNERS WITH THE NEMA NU -4 IMAGE QUALITY PHANTOM USING A COLLECTION OF RADIOISOTOPES
Rik Nezich 1,2 , Anthonin Reilhac 3 , David Zahra 3 , Roger Price 1,2 1 Radiopharmaceutical Production & Development (RAPID) Laboratory, Medical Technology and Physics, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia
2 School of Physics, University of Western Australia, Western Australia, Australia
3 ANSTO Life Sciences, ANSTO, Lucas Heights, NSW, Australia
Background: The radioisotopes 18 F, 11 C, 124 I, 68 Ga, 89 Zr and 64 Cu have found numerous applications in small animal PET imaging, and this entire subset of isotopes will soon be available to Australian preclinical researchers. The suitability of an isotope for a given imaging application is determined largely by its radioactive half-life. However, other characteristic physical properties of the isotope such as the branching fraction and positron energy can severely impact image quality and the ability to accurately quantify uptake of the radio-labelled molecule. Furthermore, the specifi c acquisition parameters and reconstruction algorithms employed to generate the image can signifi - cantly affect the image quality and quantifi cation accuracy.
The NEMA NU-4 2008 standards describe a method to evaluate the per- formance of small animal PET scanners. The information gathered through the NEMA Image Quality phantom scanning experiment is valuable for optimising the scanner usage, because it allows for the best selection of acquisition/reconstruction protocols and provides knowledge of the resolu- tion limits of the system.
Method: NEMA NU-4 image quality phantom performance testing was performed on the Siemens Inveon with 18 F, 124 I and 64 Cu, using default acquisition parameters and each of the available reconstruction algorithms.
Further testing will be performed using 11 C, 68 Ga and 89 Zr. The Bioscan NanoPET scanner will be tested with all of the mentioned isotopes.
Results: The fi gure shows NU-4 phantom images obtained for 18 F, 64 Cu and
124 I; using the Inveon preclinical scanner and FBP2D reconstruction. The relatively poor image quality obtained with 124 I is mainly caused by single gamma-photon contamination. Due to a higher positron range, recovery coeffi cients obtained with 124 I are well below the values measured with 18 F.
Conclusion: NEMA NU-4 performance testing provides valuable informa- tion about the image quality achievable for a given PET scanner and radioisotope.
P07
A TECHNIQUE TO REDUCE LUNG AND LIVER MISREGISTRATION IN PET / CT
Anna Nowicki , Shakher Ramdave , Lisa Bowker , John McKay , Jason Bradley
Southern Health, Melbourne, Victoria, Australia
Background: A common problem when interpreting PET/CT results is the misregistration that occurs from breathing artefact. Artefact occurs as a result of the tidal breathing patterns throughout the PET acquisition. New technol- ogy and techniques are constantly evolving to improve breathing artefact in order to allow better interpretation of scans.
Aim: The respiratory gating system employed in our PET/CT is very time consuming and result in long scan times. In a busy department additional acquisitions create time management problems due to high patient through- put. Our aim was to fi nd an alternative simple protocol to reduce breathing artefact.
Method: A one bed static acquisition was acquired following a whole body PET/CT scan with signifi cant misregistration in either a lung or liver lesion.
The patient is placed on the bed supine, with a fi rm strap around their lower chest. Instructions are given to breathe using their upper chest wall in isola- tion, limiting diaphragmatic motion. The patient is put on 2 litre of oxygen to allow for better oxygenation, and to reduce any distress to the patient. A1 bed PET/CT is acquired over the region of interest at 2/mins per bed to allow for enough counts but reduced time for patient.
Results: Our new breathing acquisition has vastly improved PET to CT data registration and in a majority of patients providing a more accurate localisa- tion and SUVs of lung and liver lesions.
Conclusion: Dedicated acquisitions to reduce breathing artefact can be an effective way of reducing misregistration in departments that are time poor or respiratory gating is unavailable.
P08
PRE-CLINICAL IMAGING DEVELOPMENTS AT THE ACRF CENTRE FOR TRANSLATIONAL CANCER RESEARCH AND IMAGING
Graeme O ’ Keefe 1 , Sylvia Gong 1 , Kevin Hickson 1 , Angela Rigopoulos 2 , Diana Cao 2 , Mark Frewin 2 , Andrew Scott 1,2
1 Austin Health, Melbourne, Victoria, Australia
2 Ludwig Institute for Cancer Research, Melbourne, Victoria, Australia
Background: Progress on the Pre-clinical imaging capability at ACRF Centre for Translational Cancer Research and Imaging is reported following the completion of a dedicated Animal house facility and more recently, the
commissioning of three key platform technologies; Optical (Bio-Lumines- cence and Bio-Fluorescence), micro-PET/MR and micro-SPECT/CT.
Method: Performance characteristics for the PET/MR and SPECT/CT systems are measured and reported. Image data are presented for qualitative review. Research capabilities are discussed.
Conclusion: The commissioning of state-of-the-art pre-clinical platform technologies at the ACRF Centre for Translational Cancer Research and Imaging is summarised and the discussed with respect to future pre-clinical imaging potential.
P09
APPEARANCE OF 99M T C-SESTAMIBI THYROID SCINTIGRAPHY WITH CALCULATION OF THYROID-TO-BACKGROUND RATIO IN PATIENTS WITH GRAVES ’ DISEASE, TOXIC MULTINODULAR GOITRE AND HYPOTHYROIDISM
David Pattison 1,2 , James Westcott 1 , Dinesh Sivaratnam 1,3 , Meir Lichtenstein 1
1
Department of Nuclear Medicine, Royal Melbourne Hospital, Victoria, Australia
2 Department of Diabetes & Endocrinology, Royal Melbourne Hospital, Victoria, Australia
3
Department of Cardiology, Royal Melbourne Hospital, Victoria, Australia
Background: 99m Tc-sestamibi thyroid scintigraphy ( 99m Tc-STS) was recently described as an accurate tool for differentiating between subtypes of Amioda- rone-induced thyrotoxicosis (AIT), with important therapeutic implications.
Type I AIT is due to iodine induced hyperthyroidism (increased 99m Tc-sesta- mibi uptake), while Type II AIT is a destructive process (absent 99m Tc-sesta- mibi uptake). Limited information is available about the appearance and quantifi cation of 99m Tc-sestamibi uptake in other thyroid disease. This study aims to describe the appearance of the thyroid (including calculation of thy- roid-to-background ratio [TBR]) in patients with incidental thyroid disease following injection of 99m Tc-sestamibi for parathyroid scintigraphy to provide insight into the appearance of 99m Tc-STS for investigation of AIT.
Methods: Four cases of abnormal thyroid function were identifi ed during a retrospective audit of 99m Tc-sestamibi parathyroid studies performed at Royal Melbourne Hospital (Parkville, Vic) between 1 st October 2011 and 31 st December 2012. One patient had Graves Disease, two had toxic multinodu- lar goitres (MNG) and a fourth patient had hypothyroidism receiving thy- roxine replacement. Regions of interest were drawn around the thyroid, and background inferior to the gland, with subsequent calculation of area-nor- malised TBR.
Results:
Table 1 Thyroid scintigraphy following injection of 99m Tc-sestamibi and 99m Tc-pertechnetate with incidental thyroid disease
Case 1 Case 2 Case 3 Case 4
Graves ’ Disease Toxic MNG Toxic MNG Hypothyroidism
99m Tc-STS appearance Symmetrical, diffuse ↑ uptake Asymmetrical enlarged gland, heterogeneous
↑ uptake
Asymmetrical, heterogeneous uptake
Absent uptake
Adenoma Localisation R lower pole R lower pole R upper pole L lower pole
TBR 1.79 2.08 1.44 ∼ 1
99m Tc-pertechnetate study appearance
Diffuse ↑ uptake (except R lower pole)
Uptake N/A *
Heterogeneous uptake, ‘hot’ nodule in L upper pole
Uptake = 2.1%
Heterogeneous uptake (R > L) Uptake = 1.9%
N/A
L, left; R, right; *derived from parathyroid subtraction study following injection 82 MBq 99mTc-pertechnetate.
Conclusion:
1. Hyperthyroidism (increased synthesis & release of thyroxine) due to Graves ’ disease and toxic multinodular goitre demonstrates elevated TBR following 99m Tc-sestamibi injection. This is consistent with the fi ndings of
99m Tc-STS in Type I AIT.
2. Chronic hypothyroidism is associated with absent 99m Tc-sestamibi uptake.
Musculoskeletal/Infection/Infl ammation P10
IMPACT OF SPECT / CT ON GALIUM-67 IMAGING
Rosalie Babicheva , Hugh Dixson , Kien Lee , Quee Li Chiam
Bankstown-Lidcombe Hospital, NSW, Australia
Background: Ga-67 is a useful tool for the diagnosis of infl ammation and chronic infection. Our aim was to evaluate the diagnostic value of SPECT/
CT for Ga-67 studies.
Methods: Three anatomic locations were evaluated chest, abdomen and pelvis. 73 studies were performed on a 6-slice Philips Precedence camera with CT for attenuation correction and anatomic localisation. Cases were evaluated by the reporting doctor with respect to ‘change in diagnosis’, ‘more accurate diagnosis’ and ‘increase in diagnostic confi dence’.
CT effective dose (E) in milliSievert (mSv) was calculated for each patient using the formula, E = EDLPxDLP, where EDLP is the region-specifi c, DLP is normalised effective dose and DLP is dose length product.
Result: SPECT/CT changed diagnosis in 6 patients, increased accuracy of diagnosis in 45 patients, and increased diagnostic confi dence in 60 patients.
Effective CT dose ranged from 1.1 mSv to 3.01 mSv, with a mean of 2.11 mSv.
Conclusion: CT provided helpful diagnostic information which was benefi - cial in 70% of patients with little additional radiation.
P11
18 F - FDG PET IN THE EVALUATION OF INFECTION IN THE EXTREMITIES – INITIAL EXPERIENCE
Roslyn Francis 1,2,3 , Simone Culleton 1,2 , Tatiana Segard 1,2 , Peter Robins 1,2 , Peter Swift 1,2 , Elaine Campbell 1,2 1
WA PET Service, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia
2 Nuclear Medicine, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia
3
University of Western Australia, Perth, Western Australia, Australia
Background: Referrals for query infection of the extremities are common and increasing in number. The Gold Standard method for evaluating osteo- myelitis in the extremities is a 99mTc-HDP Bone scan with either 99mTc- HMPAO or 111In labelled white blood cells. These procedures are both complex and time consuming for both staff and patients. Labelling white blood cells involves handling of blood products with all the associated risks and takes 36 hours before obtaining results. Imaging time on SPECT/CT gamma cameras can take 40–60 minutes with even the smallest patient move- ment resulting in artefacts which may compromise diagnosis.
18F-FDG is used predominantly for oncology, but increased 18F-FDG activity is also associated with infection. Using 18F-FDG to assess infection in diabetic feet could potentially reduce imaging time, remove the risks associated with handling blood products, reduce the likelihood of motion artefacts, and reduce inpatient stay by providing results on the same day.
Aims: The aim of this study is to initially assess the feasibility and utility of 18F-FDG in infection of extremities.
Method: Patients referred to our department query infection of extremities who clinically require a bone scan (99mTc HDP) and a WBC scan (111In Oxine or 99mTc HMPAO) and fi t within certain inclusion criteria will be invited to participate in this study. Each patient will undergo an additional 18F-FDG PET scan of the area in question and will be followed for 3 months for treatments and outcomes. Their scans will be assessed independently and the randomly assigned Physicians will be blinded to patient outcome.
Results: Sample initial images of 18F-FDG in infection of extremities and experiences of staff and patients will be displayed.
Conclusion: This study is incomplete and ongoing and results will be reviewed upon conclusion.
P12
FDG PET / CT AND LARGE VESSEL VASCULITIS: A CASE STUDY
Laura Renshaw
Hunter New England Imaging, NSW, Australia
Background: PET/CT FDG provides a non-invasive, accurate way for diagnosis of disease, especially in cases of pyrexia of unknown origin. PET/
CT is also cementing its place as a useful diagnostic tool for patients with suspected vasculitis. PET/CT can be used to diagnose cases of large vessel vasculitis in patients who otherwise have had no successful diagnoses.
Aim/Method: Presented here is a case of a 60 year old woman with sus- pected vasculitis. She had undergone an extensive workup in the search for a diagnosis, including a left temporal biopsy, repeated pathology and a gallium scan, all of which yielded negative results. The patient underwent a PET/CT scan which fi nally diagnosed large vessel vasculitis, allowing for the patients treatment to go ahead.
Conclusion: This case highlights that for diagnosis of vasculitis, PET/CT FDG provides a highly sensitive and specifi c diagnosis tool. PET/CT is also useful for follow up imaging in these cases.
P13
AN INTERESTING APPEARANCE OF OFUJI ’ S DISEASE ON A F 18 FDG PET / CT SCAN
Laura Renshaw
Hunter New England Imaging, NSW, Australia
Background: FDG PET imaging is a well-known and established imaging tool in the fi elds of oncology, neurology, cardiology and infection. Its other uses and applications are still being discovered in research and fi ndings around the world.
Aim/Method: A patient was referred for a routine staging PET scan for left upper lobe malignancy. The patient underwent the PET scan as per protocol and the images were quite interesting. The report notes low to moderate uptake throughout the skin of the trunk as well as the lower limbs. On further questioning of the patient and investigation of past histology, these lesions were in fact eosinophillic pustular folliculitis, also known as Ofuji ’ s disease.
Conclusion: No other reported or published images could be found of a PET scan showing this chronic skin condition.
P14
PHYSIOLOGIC APPEARANCE OF POROUS ORBITAL IMPLANTS AT F -18 FDG PET - CT – PICTORIAL ESSAY
Peter Robins , Andrew Law
Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia
Background: The most common indications for orbital enucleation include the treatment of intraocular malignancy, severe traumatic injury and a blind, painful eye. Modern porous orbital implants are used following enucleation to achieve a more cosmetically acceptable result. Physiological processes that occur during integration of these implants affect the imaging appearances on F-18 FDG PET-CT.
Aim: To illustrate the appearance of porous orbital implants on FDG PET-CT imaging.
Method: From patients scanned in the Western Australian PET Service over the past 5 years, 5 patients were identifi ed with porous orbital implants. These patient ’ s images were reviewed and clinical follow-up was performed to assess any adverse outcomes in regard to the prostheses.
Results: The porous orbital implants showed signifi cantly increased FDG uptake within the prostheses in all 5 patients. No signifi cant periorbital uptake was identifi ed apart from physiological orbital muscle activity.
Increased glucose metabolism within the orbital implant was not associated with evidence of infection, tumour recurrence, or implant extrusion on fol- low-up of all 5 patients.
Discussion: Porous orbital implants are made from materials including hydroxyapatite, aluminium oxide and polyethylene. The crystalline structure of the porous prostheses allows ingrowth of healthy vascular connective tissue within 4 weeks, a process referred to as “fi brovascularisation”. This process has several theoretical advantages over biologically inert prostheses including (1) better prosthetic movement due to development of soft tissue attach- ments; (2) lower risk of prosthetic infection due to higher blood fl ow; and (3) less chance of extrusion or prosthetic migration. Direct comparison studies however, have not demonstrated a signifi cant outcome difference for porous implants over inert acrylic implants.
Conclusion: Physiological high-grade FDG activity within porous orbital implants should not be misinterpreted as implant infection or recurrent/
residual tumour.
P15
SPECT/CT : A VALUABLE TOOL IN THE DIAGNOSIS OF INFECTED CYSTS IN POLYCYSTIC KIDNEY DISEASE
Katherine Roy
Princess Alexandra Hospital, Queensland, Australia
Background: The infection of a cyst (pyocyst) within a polycystic kidney is a well-known and serious complication of Autosomal Dominant Polycycstic Kidney Disease (ADPKD). Diagnosing a pyocyst can be diffi cult because such a cyst can produce signs and symptoms that are non-specifi c. Diagnostic imaging tests are not always reliable for distinguishing pyocysts. A 61 year old woman presented to ED with nausea, vomiting, and lower back pain. Past medical history included a renal transplant due to PKD. She had a history of recurrent UTI. The patient developed fevers and decreased oxygen saturation, and had a raised CRP. Renal ultrasound, chest and abdomen x-rays found no source of infection. The patient was referred for a 67-Gallium-Citrate scan.
Results: In this patient, no appreciably abnormal uptake is noted on planar imaging. On SPECT/CT, low-grade gallium uptake is seen within several cysts in the upper and mid poles of the right kidney. They suggest the cyst infection.
Conclusion: Historically, gallium scans have a low sensitivity and specifi city for localising renal cyst infections. Because gallium is normally distributed in the liver, spleen and bone marrow, and is excreted through the kidneys and bowel, it is generally not preferred for abdominal infection. With the addition of SPECT/CT, gallium scans may be used to accurately delineate infected renal cysts complicating PKD. Such scans have advantages over standard diagnostic modalities and are very helpful in planning appropriate therapy.
P16
INCIDENTAL FINDING OF A SOFT TISSUE SARCOMA ON BONE SCAN
Kristina Wainwright , Eva Wegner
Nuclear Medicine Department Prince of Wales Hospital, NSW, Australia
Preamble: The incidental diagnosis of a soft tissue sarcoma from a Tc99m- MDP bone scan in our department has reinforced to us the importance of assessment of extra-osseous bone tracer uptake. Extra-osseous uptake of methylene diphosphonate (MDP) can occur in several physiological but also pathological processes hence its presence should always be accounted for.
Case: A 75 year old male was referred for a bone scan by his GP for investiga- tion of a 3 month history of weight loss and anorexia. Planar imaging was performed and an area of amorphous tracer uptake was noted in the proximal medial left thigh. A dedicated SPECT/CT revealed the tracer accumulation to be within a large rounded mass in the thigh musculature which contained both soft tissue and fat components. These radiological appearances were consistent with a soft tissue sarcoma. On direct questioning, the patient recalled that he had recently noticed an enlarging mass in that location. Following diagnostic imaging, a biopsy proved it to be a malignant spindle cell sarcoma. It was thought that this represented dedifferentiation of liposarcoma. The liposarcoma had presumably been present for many years before undergoing malignant transformation and thus causing the patient ’ s symptoms.
Discussion: Soft tissue sarcomas are uncommon mesenchymal tumours which demonstrate a spectrum of histologic differentiation. Their presenting symptoms are often vague but they most often occur in the thigh or retro- peritoneum. Most sarcomas accumulate Tc-99m MDP due to hypervascular- ity, dystrophic calcifi cation and/or direct tumour cell formation of osteoid matrix. The calcifi cation may range from microscopic to macroscopic and correlates with MDP uptake.
Conclusion: Several primary and secondary malignancies accumulate MDP.
Assessment of the soft tissues on a bone scan is thus essential, and will not only improve its diagnostic value but also reduce the risk of a missed diag- nosis of a malignancy particularly in patients in whom there is a high clinical suspicion.
Figure 1 Tc99m-MDP Whole Body Bone Scan obtained 2 hours following intravenous administration of 937 MBq of Tc99m-MDP.
Neurology P17
OPTIMISING BRAIN IMAGING ACQUISITION: HOFFMAN PHANTOM ANALYSIS
Culann Farrell , Marcia Wood , Christopher Rowe
Department of Nuclear Medicine and Centre for PET, Austin Health, Austin Hospital, Melbourne, Victoria, Australia
Background: For a number of years our department has been performing as many as 20 brain SPECT studies per week. A gamma camera upgrade in late 2012 necessitated a new protocol for brain imaging and the optimisation of new acquisition and reconstruction parameters incorporating new recon- struction algorithms and attenuation correction methods.
Method: A Hoffman brain phantom was fi lled with 40 MBq of activity to generate the same count rate found in the brain following a standard 700 MBq dose of 99m Tc ECD. Multiple acquisitions were then performed for differing times with both low energy high resolution (LEHR) and low energy ultra-high resolution (UHR) collimators. Acquisition Step times were at fi ve second increments from 15–30 seconds, resulting in four acquisitions for each collima- tor set. Visual assessment was then performed by a senior Nuclear Medicine Consultant for resolution, noise level and patient considerations.
Using the optimised acquisition parameters a number of reconstructions of the phantom studies were performed using Flash 3D. A variety of numbers of iterations and subsets, as well as a range of Gaussian fi lter values from 6.0–10.0 mm FWHM were used. Reconstruction was performed using both CTAC and Chang attenuation correction. Assessment was performed by the
same senior consultant, and the settings producing the best image quality were implemented. Further refi nements were made once a number of clinical studies had been performed.
Results: Initial assessment of the phantom studies led to the selection of a 20 sec/step protocol with UHR collimators. Gaussian fi lters of 10.0 mm FWHM were decided on for the CTAC and Chang reconstructions. Follow- ing evaluation of some clinical studies, high levels of image noise required the fi lter values to be increased to 11.0 mm and 12.0 mm.
Conclusion: Through the use of a Hoffman phantom we have developed an optimised brain acquisition and processing protocol which requires only minimal alteration for individual patients.
P18
IMPLEMENTATION OF 3-DIMENSIONAL RESOLUTION RECOVERY AND CTAC RECONSTRUCTION ALGORITHMS IN BRAIN SPECT IMAGING
Marcia Wood , Culann Farrell , Kevin Hickson , Bridget Chappell , Christopher Rowe
Department of Nuclear Medicine & Centre for PET, Austin Health, Melbourne, Victoria, Australia
Background: Implementation of new technologies such as 3-dimensional resolution recovery algorithms (Flash 3D®, Siemens Medical Systems) and measured CT attenuation correction (CTAC) can potentially improve image quality in the clinical arena. Validation of these technologies against previous methodologies is required to ensure correct image interpretation. As a centre with a strong neurology focus, this study seeks to demonstrate changes in Brain SPECT image quality that occur from these techniques.
Method: Hoffman phantom images and 10 sequential, clinical patient studies were processed using both OSEM and Flash3D. Attenuation correc- tion was performed using both Chang ’ s Algorithm and CTAC. The Chang Algorithm used manually set 4-point ellipses in phantom studies, and auto- matic threshold edge detection in clinical studies. Four datasets were gener- ated per patient and analysed using PMOD, a statistical analysis program.
ROI analysis was performed. Scaled, rigid matching was performed prior to subtraction analysis to demonstrate regional changes in count intensity between techniques.
Results: No signifi cant difference in counts was demonstrated between the Flash 3D and OSEM datasets for both phantom and clinical studies. CTAC resulted in a 20% increase in average counts compared with Chang ’ s Algo-
rithm in the phantom images. Clinical studies demonstrated the same effect, with an average increase of 17%. Subtraction analysis showed Hoffman phantom images using Chang ’ s algorithm for attenuation correction demon- strated increased activity in frontal regions compared with the CTAC, most prominently seen using OSEM reconstruction. Similar results were seen in the clinical studies, as shown in Figure 1.
Conclusion: Flash 3D and CTAC in Brain SPECT imaging have an effect on image quality in comparison to our previous methodology, with regional changes in counts evident. Further investigation of this is required and will be presented at the meeting.
Oncology/Therapy P19
OUTCOME OF IODINE-131 THERAPY FOR HYPERTHYROIDISM IN HOSPITAL KUALA LUMPUR MALAYSIA
Abstract withdrawn
P20
THE ROLE OF THE CLINICAL RESEARCH NURSE: A SIR CHARLES GARDINER HOSPITAL NUCLEAR MEDICINE DEPARTMENT AND WA PET SERVICE PERSPECTIVE
Tammy Hagan , Ros Francis, Elaine Campbell
Sir Charles Gairdner Hospital Nuclear Medicine Department, Western Australia, Australia
Conducting clinical trials has lead to evidence based gold standards of treat- ments and imaging within nuclear medicine. Trials are run in conjunction with other specialities or within the department. Over the past 5 years the number of internal departmental clinical trials has increased and this has lead to the role of the Clinical Research Nurse (CRN). The poster will cover the CRN role in the clinical trials of:
• 11 C-Methionine and 18 F-Fluorothymidine PET-CT imaging in suspected residual or recurrent glioma.
• Apoptosis Imaging in Malignant Pleural Mesothelioma.
• Evaluation of FDG PET-CT in the Infection of Extremities.
• Comparison between Ga-68 citrate PET-CT and Ga-67 citrate SPECT/
CT for Infection Imaging.
Figure 1 Effect of reconstruction on image quality. (A) Hoffman Phantom images. (B) Patient data demonstrating similar effects.
The CRN role is multifaceted and varies between trials. Each trial has its own requirements and demands.
In this new and developing role many areas covered are protocol development and evaluation, recruitment and consenting of patients in trials, administer- ing radiopharmaceuticals. Trials involve covering one or more sites, often multiple departments and personnel. Meeting the demands of the CRN role a nurse requires knowledge of nuclear medicine, positron emission testing, good clinical practise, epidemiology and biostatics.
P21
INCIDENTAL FINDING OF METASTATIC MEDULLARY THYROID CARCINOMA DEMONSTRATED ON PARATHYROID SCINTIGRAPHY WITH 18 F - FDG PET CORRELATION
Abstract withdrawn
P22
MINIMISING BROWN FAT UPTAKE IN 18 F - FDG PET SCANS
Penelope Maton , Roslyn Francis
WA PET Service, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia
The uptake of 18F-FDG by brown adipose tissue (BAT) in adult humans has been documented in the literature since about 2002. Initially thought to be prevalent only in younger, slim females and dependent on ambient tem- perature, more recent reports include a wider range of patient demographics and dependence of uptake on ambient temperature has not been proven.
Uptake of FDG in BAT may lead to false positive PET scans, especially in the regions of the neck and diaphragm. Although the use of a concurrent CT scan for anatomical localisation is now the norm and can improve confi dence in reporting abnormal uptake in these regions, there are many cases where reduction of BAT uptake of FDG is the best or only strategy for certainty.
The administration of 20 to 80 mg of propanolol, 60 to 120 minutes prior to FDG administration is reported to be effective. We present recent cases where 20 mg of propanolol administered 60 minutes prior to FDG adminis- tration with patient warming from the time of propanolol administration to the time of the PET/CT scan has greatly reduced or eliminated the BAT uptake of FDG, and has infl uenced scan interpretation. Our standard prac- tice is now to fl ag patients with signifi cant BAT uptake (and no contraindica- tions) for a propanolol protocol for follow-up scans.
P23
LIFE CHANGING LUTETIUM-177
Davina Nicholls
The Queen Elizabeth Hospital, Adelaide, South Australia, Australia
Background: 59 year old woman with metastatic neuroendocrine tumour (NET) complicated by; high volume diarrhoea ( ∼ 4 L/day); hypotensive epi- sodes; exacerbation of fl ushing; weight loss – 16 kg in 4 months; and hospi- talised continuously for 3 months. She remained poorly responsive to very high doses of somatostatin antagonist (SSA) and failed Trans Arterial Chemo Embolisation (TACE). Total Parental Nutrition (TPN) with extra SSA was prescribed. She was referred to The Queen Elizabeth Hospital, South Aus- tralia, for Peptide Receptor Radionuclide Therapy (PRRT).
Method: The patient received 4 cycles of 7000 Mbq 177 Lu (Lutetium Octreotate) every 8 weeks. Pre-medications for nausea were given and intravenous amino acids were administered for renoprotection. Whole Body SPECT/CT imaging was performed 24 hrs post 177 Lu administration.
Serial Quality Of Life (QOL) data was recorded over the 6 months of therapy.
Results: There was dramatic clinical and biochemical response as early as 3 weeks post fi rst dose of 177 Lu. This enabled cessation of TPN, with reduction and eventual cessation of the high doses of SSA. She was able to resume a normal diet, the diarrhoea was markedly reduced and she began to put on weight. Throughout her 4 cycles, imaging and QOL surveys docu- mented the improvement in both tumour burden and quality of life, respectively.
Conclusion: This patient had exhausted all standard treatment preferences in an attempt to control her severe complications from progressive metastatic NET – rendering her hospitalised. Treatment with PRRT offered this patient a dramatic improvement in her quality of life; enabling discharge from hos- pital; cessation of costly TPN + SSA; resumption of oral dietary intake and a functional return to activities of daily living.
Although PRRT is rarely given with curative intent, it is an invaluable means of improving QOL. Lutetium should not be underestimated as a worthwhile treatment benefi ting both the patient and the healthcare system.
P24
EFFECTS OF ALTERED INJECTION TECHNIQUE ON BREAST LYMPHOSCINTIGRAPHY RESULTS
Stephanie O ’ Donnell , Georgina Santich , Geoffrey Bower
Mount Nuclear Medicine, Western Australia, Australia
Background: Mount Nuclear Medicine performs a large number of breast lymphoscintigraphy studies for Sentinel Lymph Node (SLN) localisation. We were asked to change our primary injection technique from peritumoural (PT) using 4 × 0.25 mL, total 40 MBq to periareolar (PA) with 1 × 0.5 mL, total 30 MBq of antimony sulfi de colloid as part of a planned study substitut- ing radiolocalisation with an 125 Iodine seed instead of hookwires for locating impalpable tumours. Intradermal injections were used when time was limited and no SLN had been visualised.
Method: We reviewed results from a previous six month period of PT injec- tions and then for the following six months of subcutaneous PA injections.
Our standard SLN imaging protocol was used for both groups of patients.
Imaging was performed on a dual head GE Myosight gamma camera or a single head DigiRAD Ergo gamma camera. We then resumed PT injections and reviewed the most recent six months of results.
Results: The success rate of visualisation of a SLN remained reasonably high (87.5% of 96 PA versus 93% of the 167 PT injection groups) and the time taken to identify the SLN was similar. Both groups showed 99% visualisation of the SLN following intradermal (ID) injection. The rate of drainage to internal mammary lymph nodes was considerably reduced however as PA showed only 6% of patients with IM nodes (PT showed 23%). In the recent six months SLN visualisation was 73.3% PA and 87.2% PT. With ID injec- tion results were 87.5% and 98.3% respectively.
Conclusion: We found that the depth and / or site of injection makes a signifi cant difference to SLN drainage patterns. PT injection or deeper PA injection, at the same depth as the cancer, as well as delayed imaging should identify an appropriate rate of internal mammary node drainage.
P25
68 G A- DOTA -OCTREOTATE PET AND PET PROBE-GUIDED SURGERY IN THE LOCALISATION AND TREATMENT OF GASTRINOMA
Brenton O ’ Mara , Nelson Loh , Shayne White , Mikael Johansson , Spiro Raftopolous
Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia
Background: We report a case of gastrinoma that was successfully resected under radio-guidance following 68 Ga-DOTA-Octreotate PET imaging. The case highlights the early sensitivity of 68 Ga-DOTA-Octreotate PET in spite of normal anatomical imaging studies (MRI, CT, EUS), and the utility of Octreotate PET and PET probe-guided surgery in the localisation and treat- ment of gastrinoma.
Methods: The patient presented with Zollinger-Ellison syndrome diagnosed on clinical and biochemical grounds with a diagnostic secretin stimulation test. Initial anatomical imaging (CT, MRI and EUS) was unable to detect a lesion. The treating team requested 68 Ga-DOTA-Octreotate PET imaging.
Results: 68 Ga-DOTA-Octreotate PET demonstrated a persistent Octreotate- avid focus between the uncinate process of the pancreas and the inferior vena cava with no further Octreotate-avid lesion identifi ed to suggest disseminated disease. The patient underwent surgical exploration following re-administra- tion of 68 Ga-DOTA-Octreotate. A 6.5 mm neuroendocrine tumour within a lymph node posterior to the uncinate process of the pancreas was successfully detected with a PET probe and removed. The patient reported signifi cant clinical improvement in the early post-operative period. We are awaiting clinical follow-up to confi rm a complete biochemical and PET response.
Conclusion: 68 Ga-DOTA-Octreotate PET has high early sensitivity in the localisation of gastrinoma and other types of neuroendocrine tumour and may facilitate surgical localisation. Early anatomical imaging modalities were negative despite early visualisation of the Octreotate-avid lesion with PET imaging. The surgical team acknowledges that resection of the lesion would have been extremely diffi cult without assistance of a PET probe.
P26
INCIDENTAL FOCAL THYROIDAL 18 F - FDG UPTAKE ON PET - CT : HISTOPATHOLOGICAL CORRELATION
Andrew Robertson 1 , Dee Nandurkar 1 , Ian Jong 1 , Shakher Ramdave 1 , Geoffrey Soo 1 , Jason Bradley 1 , Michal Schneider-Kolsky 2
1 Department of Medical Imaging, Monash Medical Centre, Victoria, Australia
2 Department of Medical Imaging & Radiation Sciences, Medicine, Faculty of Nursing and Health Sciences, Monash University, Victoria, Australia
Background: Increasing use of 18F-fl uorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) has resulted in increased incidental fi ndings of focal thyroidal FDG uptake. Previous studies performed overseas suggest a high risk of malignancy in these incidentally detected thyroid lesions.
Aims: To determine (i) the proportion of patients undergoing PET-CT for assessment of nonthyroid cancer in an Australian metropolitan hospital setting who have focal thyroidal FDG uptake; (ii) the proportion of these patients who undergo fi ne needle aspiration biopsy (FNAB) of the thyroid lesion, hemithyroidectomy or total thyroidectomy; and (iii) the proportion of these patients with incidentally detected thyroid malignancy.
Methods: A retrospective audit of all PET-CT studies performed at South- ern Health between February 2011 and January 2013 was performed.
Patients undergoing PET-CT for assessment of nonthyroid cancer with an incidental fi nding of focal thyroidal FDG uptake were identifi ed from our database. Patient medical records, Radiology and Pathology databases were reviewed to identify patients who had been further investigated with FNAB of the thyroid lesion, hemithyroidectomy or total thyroidectomy.
Results: Of 4395 PET-CT studies performed at Southern Health, 2.5%
(112/4395) demonstrated focal thyroidal FDG uptake. 42% (35/84) of patients undergoing PET-CT for assessment of nonthyroid cancer with focal thyroidal FDG uptake had been further investigated with FNAB, hemithy- roidectomy or total thyroidectomy. 17% (6/35) had a malignant cause for their focal thyroidal FDG uptake. Causes included follicular thyroid carci- noma (n = 2), papillary thyroid carcinoma (n = 2), medullary thyroid carci- noma (n = 1), and metastatic lung carcinoma (n = 1). The remaining 83%
(29/35) were benign. Causes included hyperplastic nodules, colloid nodules and follicular adenomas. The average SUV max of malignant lesions (8.9) was not signifi cantly different from that of benign lesions (6.2).
Conclusion: All patients undergoing PET-CT with an incidental fi nding of focal thyroidal FDG uptake should be recommended for further investigation with ultrasound-guided FNAB of the thyroid lesion in the fi rst instance.
Paediatric P27
IMAGING PITFALL – RETRACTILE TESTIS IN PAEDIATRIC LYMPHOMA: CASE REPORT
Peter Robins , Andrew Law
Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia
Aim: To highlight an imaging pitfall in characterising groin masses in male paediatric patients on PET-CT and to discuss the differential diagnosis.
Method: A 5 year old male patient underwent PET-CT imaging with F-18 FDG under general anaesthetic for restaging of treated Hodgkin ’ s disease of the left inguinal region.
Results: PET-CT demonstrated mildly increased FDG activity in a new 12 mm soft tissue mass in the left groin that was suspicious for recurrent disease. The lesion had an elongated ovoid appearance and the low dose CT localised the mass to the left inguinal canal. Further analysis revealed only one testis within the scrotum, although a previous PET-CT scan had shown both
testes within the scrotum. The left inguinal mass was therefore correctly identi- fi ed as a retractile (rather than undescended) testis, which is a physiological fi nding at this age. In the absence of abnormal uptake elsewhere, the diagnosis of a complete metabolic response was confi dently made and inappropriate biopsy of the left inguinal mass was avoided, saving the young patient and his family signifi cant distress and another general anaesthetic.
Discussion: The differential diagnosis of an inguinal mass in male patients includes lymphadenopathy (malignant, infective or infl ammatory), hernia, aneurysm (false or true), varicocoele, spermatic cord lipoma/hydrocoele, as well as a malpositioned testis. Assessing the metabolic activity increases specifi city in characterising the mass on PET-CT.
Conclusion: A retractile or undescended testis should always be considered in the differential diagnosis of a metabolically active soft tissue mass along the line of the inguinal canal in the appropriate clinical setting.
P28
MANAGING PATIENT ANXIETY IN PAEDIATRIC NUCLEAR MEDICINE
Katherine Stanton 1 , Tracy Benger 1 , Rapsodie Barbour 2 1 Nuclear Medicine, Women ’ s and Children ’ s Hospital, South Australia, Australia
2
Centre for Health Promotion, Women ’ s and Children ’ s Health Network, South Australia, Australia
Background: Paediatric Nuclear Medicine requires patient cooperation to obtain an optimal scan. We have observed high levels of patient anxiety induc- ing lack of cooperation. This is caused by injection fear and the necessity to remain still and can be exacerbated over multiple appointments. Environ- ment, lack of availability of distraction devices and failure to explore alterna- tives are contributing factors. We aimed to promote a healthy outcome psychologically for children attending our department.
Method: In response to this identifi ed need, we applied for a Health Promo- tion grant which funded the project and allowed us to work with a mentor from Health Promotion. Evidence in the literature demonstrates the benefi ts of employing distraction techniques for painful procedures including veni- puncture on children. We purchased an IPad, bubble machine and “Buzzy Bee” injection distractor and documented the benefi ts of these devices in our department.
Results: Qualitative evaluation was conducted through surveying patients, parents and staff. Responses showed that the use of distraction devices in Nuclear Medicine was helpful to reduce patient anxiety levels. Using interac- tive applications on the IPad allowed for effective distraction of children to reduce their focus on the injection. Through working with the Health Promo- tion unit, staff in our department improved research and project skills. We were able to adjust our working practice to accommodation our patient ’ s needs through applying health promotion methodology.
Conclusion: High patient anxiety levels may compromise the quality of a Nuclear Medicine study, particularly in the paediatric cohort. Through research and stakeholder consultation, we have implemented effective tech- niques to reduce patient anxiety. This collaborative project has encouraged our staff learn about health promotion and associated models of healthcare relevant to reducing anxiety in children having Nuclear Medicine scans. It has enabled us to employ a holistic approach to health within our department for the benefi t of our patients.
P29
FLT IN PAEDIATRIC BRAIN TUMOURS
Russell Troedson 1,2 , Elizabeth Thomas 1,2 , Nick Gottardo 2 1 WA PET Service, Western Australia, Australia
2 Princess Margaret Hospital for Children, Western Australia, Australia We present 2 children with brain stem gliomas who were evaluated with F18 FLT PET imaging.
Background: Patient 1. A 13 yo boy on holiday in Singapore presented to hospital semi comatose. MRI showed a 3 × 2.6 cm mass in the posterior fossa with hydrocephalus. He underwent emergency EVD insertion and was trans- ferred to PMH. A Neurosurgical opinion advised against biopsy.
An F18 FLT study showed moderately intense uptake with Maximum SUV 1.56 supporting a high grade tumour.
The patient was commenced on radiation therapy with a rapid and marked response supporting the presumption of a high grade tumour ( likely glioma).
Patient 2. A 2 yo girl with progressive stridor onset at 6 months of age. ENT review with fi breoptic exam following adenotonsillectomy noted vocal cord paralysis. Urgent MRI showed a large cervicomedullary tumour. One year following initial treatment tumour progression was diagnosed. F18 FLT imaging showed moderate uptake with SUV max 0.86 ( intermediate).
Debulking surgery was undertaken and pathology revealed ganglioglioma with ki-67 positive in up to 5% of tumour cells. There was tumour progres- sion in keeping with high grade tumour. Patient commenced on focal radio- therapy and oral temozolomide.
Methods: F18 FLT PET-CT imaging was undertaken 1 hour post tracer injection. Uptake within the tumour was identifi ed and maximum SUV was measured.
Results: The tumours were clearly identifi ed in both patients. Maximum SUV measurements were in the non low grade range.
Clinical progress for both patients was in keeping with high grade tumours.
Conclusion: PET assessment of brain tumours has the potential to be a useful assessment tool.
Greater uptake on an FLT study may predict a high grade tumour and allow commencement of therapy prior to tumour progression. Assessment of appropriate quantitation parameters and cut off values in further paediatric studies would be helpful.
Physics/Instrumentation P30
ACTIVITY MEASUREMENT OF YTTRIUM-90 MICROSPHERES IN DOSE CALIBRATORS – THE INFLUENCE OF VOLUME AND DENSITY
Nicholas Forwood 1 , Dale Bailey 1,2 , Kathy Willowson 3
1 Nuclear Medicine Department, Royal North Shore Hospital, Sydney, NSW, Australia
2 Faculty of Health Sciences, University of Sydney, Sydney, NSW, Australia
3 School of Physics, University of Sydney, Sydney, NSW, Australia
Background: Yttrium-90 labelled microspheres, used in the treatment of liver cancer, have historically been diffi cult to calibrate in nuclear medicine departments. A recommended method is to measure the activity of the microspheres in the glass shipping vial using a dose calibrator and then measure residual activity after drawing out the required volume for treatment.
This research examines how the response of the dose calibrator varies with the volume and density of solution in the vial.
Method: To determine the dependence of the dose calibrator ’ s (Capintec 55TW) response on the volume of the sample, a solution of ∼ 1100 MBq of Yttrium-90 chloride was assayed in a standard microspheres shipping vial while increasing the volume in 0.2 mL intervals, but keeping the total activity constant. In addition the solution on top of an unused dose of Yttrium-90 labelled microspheres was removed and the microspheres were shaken until they reached a uniform suspension and then the activity in the vial was assayed as water was added in 0.2 mL increments, while the total activity remained constant.
Results: The dose calibrator overestimated activity as the volume of the solution was decreased. When the activity was in the microspheres suspended in water an almost identical over-response was observed as the volume changed. No signifi cant effects of density of spheres in the dose calibrator response were observed.
Conclusion: The dose calibrator has a signifi cant relative response variation with volume of the measured sample, and measures of residual activity fol- lowing with withdrawal of Yttrium-90 treatment dose should be corrected for the change in volume. If the density of the microspheres in the suspension did have an effect on the response of the dose calibrator it was too small to be observed in this experiment.
P31
THE AUTOMATED MONITORING TOOL FOR MANAGEMENT OF QC / QA RESULTS IN NUCLEAR MEDICINE/ PET SERVICE – SCGH
Andrea Giacomet , Jan Boucek , Paul Brayshaw
Nuclear Medicine/PET Service – Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia
Background: The Nuclear Medicine and PET service at Sir Charles Gairdner Hospital is a large department with three SPECT/CT and two PET/CT scan- ners, and has a QC program that includes daily and other, less frequent, tests.
Results are saved on separate acquisition computers, making monitoring and analysis time-consuming and laborious. Moreover, results are kept only for a certain period, after which they are automatically deleted. We designed and implemented an automatic QC monitoring system that logs and analyses QC results to (i) ensure a permanent record of QC data, and (ii) check not only the immediate conformance, but also the trend of QC results over time.
Method: Visual Basic and Windows Scripts were written to automatically back up QC results from the acquisition computers to a network drive. The
Figure 1 Relative dose calibrator response for Yttrium-90 in solution and Yttrium-90 microspheres.
back-up fi les were assessed using front-end tools developed in MS Access and MS Excel to extract relevant QC information, insert it into the database and manage results.
Results: A permanent, backed-up record of all scanners QC data was created on a department shared drive. Tabulated data facilitated analysis and the scheduling of tests. The ability to view trends in QC results at a glance assisted in the timely detection of problems, even if results were within the tolerance interval, e.g. a sudden variation on the trend of Scatter Ratio Values was detected on a PET/CT scanner:
Conclusion: The automated monitoring tool has become an integral part of our QC program. It facilitates the organisation and control of QC testing, and the monitoring of QC results warns of possible problems with the equip- ment before they manifest, allowing timely intervention. Faster detection of QC problems has improved communication and feedback of technical issues to vendors and technologists.
P32
NEMA NU 2 2007 PERFORMANCE MEASUREMENTS AND COMPARISONS OF 2ND AND 3RD GENERATION GEMINI TIME-OF-FLIGHT PET / CT SCANNERS
Kevin Hickson , Graeme O ’ Keefe , Sylvia Gong , Andrew Scott
Austin Health, Melbourne, Victoria, Australia
Background: In this study we present a comparison of the performance of two recently installed Philips GEMINI TF PET/CT scanners, one Gemini TF Generation 2 scanner (TF64) and one Gemini TF Generation 3 scanner (TF128). The PET component in both of these scanners uses lutetium-yttrium oxyorthosilicate (LYSO) crystals in a fully 3-dimensional mode with good timing resolution to operate as a time of fl ight scanner.
The TF128 also incorporates High Throughput Acquisition (HTA), which increases the high-count rate capabilities of the TF128 compared to the TF64. The timing resolution of the TF64 and TF128 is reported to be 575 ps and 495 ps respectively [1].
Method: Performance measurements on the scanner were made using the National Electrical Manufacturers Association (NEMA) NU2-2007 proce- dures to benchmark the scanners conventional imaging capabilities.
Results: It was found that with the incorporation of HTA and faster elec- tronics a higher noise equivalent count rate was maintained for the TF128 compared to the TF64. The spatial resolution and image quality of both scanners was increased compared to the PET department ’ s original Gemini PET/CT scanner.
Conclusion: The installation of these new PET/CT scanners is a valuable addition to the departments imaging capabilities. The incorporation of HTA into the TF128 PET/CT is particularly valuable for clinical studies that require a high injected activity for example Rb-82 cardiac studies.
1. NEMA Standards Publication NU 2-2007 . “ Performance Measurements of Positron Emission Tomographs ”, Published by National Electrical Manufacturers Association (NEMA), 2007.
Radiation Safety P33
A PRELIMINARY REVIEW OF PET DOSE DISPENSING PRACTICES WITH EXTREMITY MEASUREMENTS
Gordon Chan , Kenneth Young , Sylvia Gong , Kevin Hickson , Andrew Scott
Austin Health, Melbourne, Victoria, Australia
Background: Due to handling unsealed radioactive sources, extremity doses are a major concern to nuclear medicine staff. The hand exposure to radio- pharmacists dispensing PET doses was reaching maximum allowable limits and a semi-automated syringe dispenser was instigated for dispensing FDG doses. A signifi cant twenty-fi ve times reduction in doses resulted.
However it is not practicable to use the dispenser system for research com- pounds and it is estimated that this was now contributing around 70% of extremity doses. Thus a preliminary review of PET dose dispensing practices was undertaken.
Method: Two experienced operators manually dispensed 20 syringes of PET radiopharmaceutical each, 10 syringes without a syringe shield and 10 with.
The activity to be dispensed was 10 mCi (370 MBq), a commonly used dose for research. The operators were timed and the dispensed activities recorded.
Exposure measurements were recorded using the instadose™ dosimeter worn around the wrist of the dominant hand.
Results: The results show the same extremity exposure rate and time taken by both operators to dispense unshielded syringes. Operator A ’ s exposure rate was 30% less when dispensing using a syringe shield, however their dispensing time increased threefold. Operator B ’ s exposure rate only decreased by 10.5% when dispensing shielded syringes, probably due to the syringe being removed from the shield when removing the air bubble because of diffi culty with visualisation through the syringe shield lead glass. However the easier air removing procedure resulted in only doubling the unshielded syringe dispensing time.
Conclusion: Dispensing PET radiopharmaceuticals with shielded syringes can lead to a signifi cant reduction in hand exposure. However there is a signifi cant increase in dispensing time due to the awkwardness of handling a heavy shield and diffi culties with visualisation through the lead glass.
Decreasing exposure time is not as effective as shielding. Further investiga- tion is warranted.
Scatter Ratio
28.8 29.8 30.8 31.8 32.8 33.8 34.8
20/03/12 29/04/12 8/06/12 18/07/12 27/08/12 6/10/12 15/11/12 25/12/12 3/02/13
%
Figure 1 Scatter Ratio – Biograph mCT.